Field of the Disclosure
Embodiments of the present disclosure generally relate to the fields of geology, geophysics, and geomechanics.
Description of the Related Art
Wellbore operations in intricate geologic environments, such as those in deep water subsalt plays, complicated in-situ stress domains, and tight gas shale, can bring unexpected problems. One way to manage these problems is to develop a very thorough geomechanics model of the subterranean condition and the proposed well trajectory, and to use the model to plan the associated wellbore operations.
Wellbore stability, sand control, and hydraulic fracturing are three challenges that need to be managed. Each challenge requires different considerations for the choice and control of critical operating parameters in order to carry out a trouble-free operation.
Solutions to these challenges, as well as others known in the art, require a reliable subterranean geomechanical model that is constructed from geological and geophysical models in order to estimate and control the range of critical parameters for optimal execution of wellbore operations. The geological model may consist of stratigraphic, sedimentary, diagenetic and structural units in a subterranean model that may include anhydrite, argillaceous, carbonate, salt and siliciclastic formations. To correlate geophysical data in defining the stratigraphic units, biostratigraphy, chemiostratigraphy, chronostratigraphy, lithostratigraphy or sequence stratigraphy can be used.
In complex geologic environments, those correlations are not reliable, and there are no accepted procedures to obtain a geomechanical subterranean model from geological and geophysical models. Most procedures ignore the statistical nature of building a geomechanical model even though geostatistical methods are commonly used in such applications. See, for example, the petrophysical model outlined in Geostatistical Reservoir Modeling, by Deutsch C. V., Oxford University press, New York, 2002. Furthermore, established geostatistical techniques for extrapolating scalar quantities such as porosity and permeability are known, but techniques for extrapolation to vector and tensor quantities, such as anisotropic rock property tensors, are lacking. Also, core and plug sample measurements are typically not helpful in constraining parameters since they are sparse or of poor quality. Consequently, many of the conventional procedures can converge to the wrong solutions
There is a need, therefore, for a geostatistical method for building a geomechanical model in anisotropic and heterogeneous complex media. There is also a need to apply the geomechanical model to predict the appropriate wellbore operational parameters required to maintain borehole stability in such environments during different operational phases.